Pathology tests database

Sample and container requirements

Plain serum

Minimum volume required

4 ml Blood

Special requirements

Patient preparation

None

Sample viability

To be stored at -70oC or below.

Turnaround time

up to 4 weeks

Reference range

Normal >75 % Abnormal <75 %

Clinical guidance

AP50 is a functional measure of alternative complement pathway activity. The Alternative complement pathway is an enzyme cascade dependent on stabilisation of C3b on microbial membranes. Low AP50 values may be caused by complement consumption or deficiency of complement components or regulatory factors. Deficiencies of membrane attack complex components would lead to absent AP50 and CH50 results, whereas Factor B, D and properdin deficiencies would show normal CH50 values in the absence of AP50 activity  Suspected complement deficiency should be investigated in anyone with an unusual strain of neisserial meningitis or recurrent infections with encapsulated bacteria https://labtestsonline.org.uk/tests/complement

Notes